From an interview with Doug Irwin about Jerry Garcia's guitars:
DI: I used a lot of Schaller stuff, exclusively Schaller tuning stuff on all of Jerry's guitars.
SQ: Any particular model number?
DI: Well the M6, M6G because I got the gold-plated. Jerry had an unusual body chemistry. Of all the people that I've worked on guitars for, I've worked on guitars for a lot of people, Jerry had the most corrosive sweat.
SQ: What effect did that have?
DI: Actually it was kind of interesting because he can eat through chrome nickel plating in three weeks. I'm not kidding you, this is like what bumpers of cars are made out of you know, it's resistant. But gold, he didn't react to, and it lasted a long time.
SQ: I wonder what caused that to happen?
DI: Well, just the fact that human beings are all similar, but we're all different. Body chemistry from individual to individual varies quite a bit. The gold tuning gear was really, I mean that's one of the reason that I used Shallers because they really do incredible plating and stuff like that. When they do gold plating on something, they don't fool around. The gold really lasts a long time, they use such a nice shade of gold, too. There's 21 colors of gold in natural shades.
But Germans are really good at making metal stuff. It's kind of the only thing they had to work with. They're sitting on top of the iron triangle and it's not a good farming region, so what do you do? ...
http://dozin.com/dougirwin/interviewpg3.html As a repairman, I can vouch for the fact that a lot of people oil their fingerboards every time they play. it's a lot more widespread than you'd think. The bassist Billy Sheehan has to wear TWO wristbands on each hand to keep the flow of grease and corruption in check.
I have a small plastic box filled with the desiccated grease and finger scum scraped off Joe Walsh's fingerboards from a couple of refret jobs we did for him. (The glamorous part of the job.)